In a treating process for various types of workpiece such as a semiconductor wafer, liquid crystal glass, or the like, an ionizer is used for discharging the workpiece, which is electrostatically charged. The ionizer is constructed such that a corona discharge is generated by applying a positive and negative high voltage to an electrode needle, and that static electricity is neutralized by spraying a then-generated positive ion and a negative ion with air.
In this kind of ionizer, the electrode needle tends to have a stain due to adhesion of dust or the like, and when the adhesion of the stain proceeds, a generating amount of the ion is being reduced because the corona discharge gradually becomes difficult to be generated. Therefore, there is a possibility that the generation of the ions is finally stopped. Therefore, this requires maintenance such as a cleaning operation, an exchanging operation, and so forth for the electrode needle in each time when the electrode needle has the stain. In order to perform the complicated maintenance, as simply and safely as possible, it is important that the electrode needle is configured to be detached from a housing portion simply and safely.
In the Japanese Unexamined Patent Application Publication No. 2004-228069, an ionizer where an electrode needle unit is configured to be detachable from a main body case is disclosed as an ionizer in which maintenance for a discharge needle (electrode needle) can simply be performed. This ionizer is configured such that a nozzle provided with an air-blowing outlet serving as an ion-generating chamber is provided in the main body case. The ionizer is further configured such that a printed circuit board where a high voltage generating circuit for applying a high voltage to the electrode needle is mounted in the main body case, and that the electrode needle unit is configured to be detachable from a rear side of the nozzle in the ion generating chamber of the nozzle. By this construction, when the electrode needle has the stain, the cleaning operation and the exchanging operation for the electrode needle can be performed by detaching the electrode needle unit from the nozzle.
However, since the ionizer described in the Patent Document is formed with all of electricity-relating parts or portions such as a printed circuit board where the high voltage generating circuit is mounted, a connector therefor, and so forth, air-relating parts or portions such as an air communication hole, connecting port for use in piping, and so forth, in the main body case in a built-in manner, a structure of the main body case tends to be complicated and large-sized at the same time, depending on a structure for disposing and electrically insulating the each of the parts or portions, or the like. Further, since it is necessary to form a structure for connecting or cutting out the electrode needle to the high voltage generating circuit in a built-in manner, when detaching the electrode needle unit, the structure therefor has been also complicated.